Persistent DUID (DHCP Unique Identifier) for Server
Simon Hobson
dhcp1 at thehobsons.co.uk
Fri Nov 25 09:04:45 UTC 2011
At 06:11 +0000 25/11/11, Madhu Krishna Sandadi wrote:
>>Bear in mind that the RFC _requires_ that the DUID_LL only be used
>>in cases where the hardware address is hard-wired, and can't be
>>changed either by changing hardware or overwriting firmware.
>I need one clarity from rfc-3315. It says from session 9.2 for DUID-LLT
>
>Clients and servers using this type of DUID MUST store the DUID-LLT
>in stable storage, and MUST continue to use this DUID-LLT even if the
>network interface used to generate the DUID-LLT is removed. Clients
>and servers that do not have any stable storage MUST NOT use this
>type of DUID.
>
>
>It says that even if we remove the network interface that used to
>generate the DUID-LLT.
>That means do we need to use the same DUID even if we replace the
>new network interface card that has new link layer address.
DUID-LLT is different to DUID-LL
LLT includes a time element, LL does not.
Thus if you were using LLT and changed the hardware - moving it to
another device - then that other device would be exceedingly unlikely
to generate the same DUID-LLT value since it's clock would be
different. Thus it would be same to continue using the same DUID-LLT
value even if your hardware address changes.
With DUID-LL, if your hardware changes, then you cannot be 100%
certain that another device won't get that hardware and generate the
same value.
--
Simon Hobson
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